JP2012085534A - Method of manufacturing electric motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electric motor in which dimensional accuracy of a stator is easily enhanced, and the effect on a magnetic circuit is suppressed as much as possible.SOLUTION: V-like cuts of which total open angle θ is larger than 360° are provided among segments 32 of a stator core, to provide such stator core in which the cuts are linearly formed in succession. When bending the stator core in ring and connecting ends together, firstly, the teeth surfaces of the segments are pressed against a post-like washer 100 while bending in ring, for first centering. Then, the stator core in ring is inserted along a first cylindrical core bar of an insulator molding metallic mold, for second centering. Then further, it is inserted along a second cylindrical core bar in an insert molding metallic mold for resin molding, for third centering. Thus, roundness of the teeth surfaces of the stator core is improved.

Description

  The present invention relates to an inner rotor type electric motor and a method for manufacturing the same, and more specifically, relates to a technique for increasing the dimensional accuracy of a stator and manufacturing a more efficient electric motor.

  A stator of an inner rotor type electric motor has a stator core in which a plurality of teeth protrude from an inner peripheral surface of a yoke formed in an annular shape toward a magnetic pole surface of the rotor, and an insulator (insulator) is provided on the outer periphery of the teeth of the stator core. ) Through which the coil is wound.

As an example of a stator core forming method, an electromagnetic steel sheet is formed by laminating an annular sheet core in which a yoke and a tooth are integrally formed in advance along the axial direction of the output shaft, and the core and the tooth are linearly arranged for each segment. There is a method of stacking straight sheet cores (straight cores) punched in a state of being connected in a shape, and connecting the ends by bending them in an annular shape.

  In the former, the stator can be formed by two processes, ie, a punching process and a lamination process. On the other hand, since the inner part of the stator is simultaneously punched from the electromagnetic steel sheet in the punching process, a lot of useless parts are generated. On the other hand, the latter has a high production efficiency because there is little such unnecessary removal.

  For example, in the invention described in Patent Document 1, a V-shaped notch is formed between the yokes of each segment in order to bend the straight core in an annular shape. By providing this notch, the deformation stress related to the straight core is concentrated on the notch, so that deformation with a smaller processing stress is possible and the magnetic circuit performance is also improved.

JP-A-9-308143

  However, the conventional method for forming a straight core type stator has the following problems. That is, the notch portion described in Patent Document 1 has an opening angle of (360 / α) when the number of teeth is α so that the gap of the notch portion becomes 0 when formed into an annular shape. However, in actuality, the end face on the base side of the notch part comes into contact at the time of bending, and stress distortion is applied thereto, so that the magnetic circuit is somewhat affected.

  In addition, since the straight core described in Patent Document 1 increases the dimensional accuracy (degree of the perfect circle of the tooth surface) when it is formed in an annular shape by attaching the two side wall surfaces of the notch, The punching accuracy of the straight core and the lamination accuracy had to be set high, and advanced production management was required.

  If the dimensional accuracy is poor, that is, the degree of perfect circle is low, it will affect the magnetic circuit of the motor and not only lower the energy conversion efficiency but also cause noise during operation of the motor due to vibration and resonance. .

  Therefore, the present invention has been made to solve the above-described problems, and its purpose is to facilitate the process of bending the straight core into an annular shape, and to easily increase the dimensional accuracy of the stator, and An object of the present invention is to provide an electric motor that minimizes the influence on the magnetic circuit.

In order to achieve the above-described object, the present invention includes a rotor having a rotation output shaft and a stator disposed coaxially on the outer periphery of the rotor, and the stator is an inner peripheral surface of a yoke formed in an annular shape. A stator core having a plurality of teeth projecting from the rotor toward the rotor, and the stator core is formed of a plurality of segments including the teeth in a straight line, and each of the segments of the stator core In the middle, when the stator core is bent into an annular shape, notches are provided to prevent the adjacent segments from interfering with each other, and each notch has a notch width from the outer diameter side to the inner diameter side. The stator core is formed in a substantially V shape that gradually spreads, and is designed so that the sum of the opening angles θ of the notches is greater than 360 °. In the manufacturing method of the electric motor formed by connecting the ends by bending in an annular shape,
A first step of bending the teeth surfaces of the segments connected in a straight line of the stator core into an annular shape while pressing the teeth surfaces against a cylindrical washer;
A second step of locking both ends of the stator core;
The stator core that has been annularized through the first step and the second step is inserted along a cylindrical first core bar provided in an insulator molding die, and an insulator is placed on each of the teeth. A third step of integrally forming;
A fourth step of applying a winding to each tooth on which the insulator is formed;
Fifth step of inserting the stator core provided with the winding along the second core metal having a cylindrical shape provided in the insert molding die, and covering the entire stator core excluding the tooth surface with resin. When,
It is characterized by having.

According to a preferred aspect of the present invention, the both ends of the stator core are provided with connecting means comprising a concave and convex fitting including a convex portion and a concave portion locked to the convex portion by caulking, and in the second step The both ends of the stator core are locked by the uneven fitting of the connecting means.

According to the present invention, first, the first centering is performed by bending the teeth surface of each segment connected in a straight line of the stator core in a first step while pressing the teeth surface against a cylindrical washer,
Next, the stator core that has been annularly formed by locking both ends of the stator core in the second step is inserted along the first cored bar that is provided in the insulator molding die in the third step. The second centering is performed by
Further, after winding in the fourth step, the resin is inserted and inserted along the second core metal having a cylindrical shape provided in the insert molding die in the fifth step. A third centering is performed by pressing the tooth surface against the second metal core at the sealing pressure, and the first, second and third centering performed in this manner allows the tooth surface of the stator core to be aligned. The degree of roundness can be further increased.

The principal part sectional view of the electric motor concerning one embodiment of the present invention. (A) Front view of stator core bent in annular shape, (b) Front view of straight core before forming in annular shape. The partial enlarged front view of a stator core. (A) (b) The enlarged front view which each expands the left end and right end of a stator core, (c) The partial enlarged view of the state which connected the edge parts. The graph showing the relationship between the clearance gap of a notch part of a stator, and energy loss. Explanatory drawing explaining the stator core bending process which shape | molds a straight core in cyclic | annular form. Explanatory drawing explaining the insulator attachment process which shape | molds an insulator in a stator core. Explanatory drawing explaining the insert molding process which integrates a stator core with resin.

  Next, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited thereto. FIG. 1 is a cross-sectional view of a main part of an electric motor according to an embodiment of the present invention, FIG. 2 (a) is a front view of a stay core bent in an annular shape, and FIG. 2 (b) is before being formed in an annular shape. It is a front view of a straight core.

  FIG. 3 is a partially enlarged front view of the stator core, FIGS. 4A and 4B are enlarged front views in which the left and right ends of the stator core are respectively enlarged, and FIG. 4C is a view in which the ends are connected to each other. It is the elements on larger scale of a state. FIG. 5 is a graph showing the relationship between the gap in the notch portion of the stator and energy loss.

  FIG. 6 is an explanatory view for explaining a stator core bending step for forming a straight core into an annular shape, FIG. 7 is an explanatory view for explaining an insulator mounting step for forming an insulator on the stator core, and FIG. It is explanatory drawing explaining the insert molding process to change.

  As shown in FIG. 1, the electric motor (motor) 1 is an inner rotor type electric motor including a rotor 2 having a rotation output shaft 21 and a stator 3 arranged coaxially on the outer periphery of the rotor 2. In the present invention, the rotor 2 may be a rotor with a permanent magnet, or any other rotor, for example, a basic configuration of an inner rotor type rotor such as a cage type or a winding type. The configuration may be arbitrary.

  2A, the stator 3 includes a yoke 31 formed in an annular shape and a plurality of teeth (magnetic pole teeth) 32a to 32a from the inner peripheral surface side of the yoke 31 toward the magnetic pole surface of the rotor 2. The stator core 30 is provided with a protrusion 32l. In this example, there are 2 × 6 = 12 teeth 32a to 32l because the induction motor has 6 poles, but the number of teeth 32a to 32l is arbitrary depending on the specification.

  The stator 3 is integrated with the resin 5 by insert molding after the coil 4 is wound.

  Each of the teeth 32 a to 32 l is covered with an insulator 33, with the tooth surface 321 at the tip being left. In this example, the insulator 33 is made of a synthetic resin insulator, and is integrally formed with the teeth 32a to 32l by insert molding.

  In this example, the insulator 33 is integrally formed with each of the teeth 32a to 32l by insert molding, but may be a separate body. For example, two insulator members divided into two in the axial direction may be attached so that the teeth 32a to 32l are sandwiched from above and below.

  A coil 4 is wound around each of the teeth 32a to 32l via the insulator 33, and the coil 4 is connected in a predetermined connection pattern. In the present invention, the connection pattern of the coil 4 is arbitrary, and the winding order and connection of the main winding, the auxiliary winding, the reduction winding, etc. may be arbitrarily selected according to the specifications.

  As shown in FIG. 2 (b), the stator core 30 has a straight core structure in which the yoke 31 and the teeth 32a to 32l are punched from the magnetic steel sheet in a state where the yoke 31 and each of the teeth 32a to 32l are linearly connected to each segment. A part of each of the yoke 31 and each of the teeth 32a to 32l is provided with a half punching hole 34 for attaching the electromagnetic steel plates to each other when the electromagnetic steel plates are laminated.

As shown in FIG. 3, between the segments of the stator core 30 (in this example, the teeth 3 2b and the teeth 32c) to, when bending the stator core 30 to the annular, the notch 35 for facilitating bending is provided .

  In this example, the stator core 30 has one straight core bent in an annular shape, but the stator core 30 may be divided. That is, for example, a plurality of stator core members formed in a rod shape having three segments as one member may be prepared, and they may be arranged and connected in a straight line. In this case, the notch 353 described later does not have to be provided at the connecting end of the core member.

  The notch 35 is formed in a V shape (inverted V shape in FIG. 3) whose opening width gradually increases from the outer diameter side toward the inner diameter side. A notch 353 is provided at the base of the notch 35 (the base of the side wall surfaces 351 and 352 of the notch 35) for concentrating the processing stress on the connecting part when the teeth 22b and the teeth 32c are bent. Yes.

  The notch 353 is formed by a notch recess notched in an arc shape on the side wall surfaces 351 and 352, and the deformation stress concentrates on the connecting portion between the segments by the notch 353, so that it can be deformed with a smaller processing stress. Instead, by forming the notch 353 in an arc shape, it can be deformed more uniformly.

  The notch 35 is designed to be larger than the total 360 ° of the respective opening angles θ. That is, in this embodiment, the number of teeth is 12, and each opening angle θ is provided to be larger than 30 °.

  In this example, the opening angle θ is designed to be 30 ° in all the notches 35, but the opening angle θ may be variable for each notch 35 such as 30 ° and 35 °, If the total sum of the opening angles θ is larger than 360 °, these modifications are also included in the present invention.

  That is, it is preferable that a minute gap is formed between the side wall surfaces 351 and 352 of each notch 35 when each of the teeth 32 a to 32 l is bent in an annular shape via the notch 35.

  By increasing the opening angle θ, the operation of bending the stator core 30 having a straight core structure into an annular shape is facilitated. That is, when the stator core 30 is bent, the stator core 30 is bent around the bending fulcrum on the connecting portion between the segments. However, if the bending fulcrum varies, the side wall surface of the notch in the conventional straight core structure May not abut in parallel and may not be able to be folded into a ring.

  On the other hand, in the case of the present invention, since the opening angle θ is large, the variation in the bending fulcrum position can be absorbed by the gap. Therefore, the straight core can be easily bent into an annular shape.

  As a more preferred embodiment, the gap is preferably in the range of 0 μm ≦ G ≦ 100 μm. According to this, since the influence on the magnetic circuit can be reduced, it is possible to prevent a decrease in energy conversion efficiency.

  That is, as shown in FIG. 5, since the relationship between the gap and the energy loss is an inversely proportional relationship, the smaller the gap G, the smaller the energy loss. However, when the gap G is 0 μm, the side wall surface during processing They may come into contact with each other and processing distortion accumulates, possibly affecting the magnetic circuit. When the gap G is larger than 100 μm, as shown in FIG. 5, the influence on the magnetic circuit is large and the energy conversion efficiency may be reduced.

  Next, referring to FIGS. 4A to 4C, connecting means 36 are provided at both ends of the stator core 30 for connecting the stator core 30 in an annularly bent state. The connecting means 36 includes a locking projection 361 provided at one end of the stator (in this example, the teeth 32a) and a locking recess 362 provided in the other end (in this example, the teeth 32l). I have.

  The locking projection 361 protrudes from the side end of the yoke 31 of the stator core 30 and is formed in a hook shape so as to be engaged by the locking recess 362. The locking recess 362 includes a pair of upper and lower clamp arms 362a and 362b that sandwich and support the locking projection 361 from the vertical direction (radial direction).

  One clamp arm 362b is formed in an open state in a straight state as shown in FIG. 4 (b). Therefore, the stator core 30 is bent into an annular shape, the locking projection 361 is brought into alignment with the clamp arm 362a, and then the clamp arm 362b is crimped and closed, as shown in FIG. The part 361 and the locking recess 362 are engaged with each other.

  Next, an example of a procedure for assembling the stator 3 will be described with reference to FIGS. In addition, the stator core 30 shall be formed in the straight shape which laminated | stacked many electromagnetic steel plates previously punched through the predetermined punching process.

  First, the stator core 30 formed in a straight shape is bent into an annular shape. As shown in FIG. 6, the stator core 30 is bent using a washer 100 attached to a predetermined bending machine formed in a columnar shape (stator core bending step).

  The washer 100 has a columnar shape that is rotationally driven by a driving means (not shown), and on the outer peripheral surface, there are engaging recesses 110 with which the tips of the teeth 32a to 32l of the stator core 30 are engaged. 12 in this example.

  Each engagement recess 110 includes an arcuate guide surface 120 formed so as to conform in shape along the tooth surface 231, and a pair of guide ribs 130 and 130 that sandwich the side end surfaces of the teeth 32 a to 32 l. It has.

  By rotating the washer 100 while sequentially matching the engagement recess 110 from one end side of the stator core 30, in this example, the rightmost tooth 32 l, the stator core 30 is gradually bent into an annular shape as it rotates. .

  Although not shown in FIG. 6, the bending apparatus is provided with a fixing means for pressing the outer peripheral surface of the stator 3 in order to prevent the stator core 30 from being violated or displaced during bending. It is preferable. The configuration of the fixing means is arbitrary.

  In this stator core bending step, when the stator core 30 is bent, the teeth surfaces 321 of the teeth 32a to 32l are pressed against the guide surface 120, thereby improving the dimensional accuracy of the stator core 30 (roundness: degree of roundness of the teeth surface). It also serves as a first centering process to increase.

  As described above, the stator core 30 of the present invention has a large opening angle θ and can be easily bent into an annular shape. Further, each notch portion 35 of the stator core 30 has a minute gap even in a state where the stator core 30 is bent in an annular shape, so that the stator core 30 is easily deformed. Therefore, since the teeth surface 231 and the guide surface 120 can be matched with high accuracy, the degree of the perfect circle of the teeth surface 231 of the stator 3 can be increased.

  According to this, compared with the conventional case where the side wall surfaces 351 and 352 of the notch 35 are brought into contact with each other and the dimensional accuracy is increased, even if the variation in the opening angle θ or the fulcrum position of the bending occurs, the teeth surface Since 231 and the guide surface 120 are made to coincide with each other and the overall distortion generated in each of the teeth 32a to 32l is removed, the dimensional accuracy can be further improved.

  After the stator core 30 is bent into an annular shape by the stator core bending step, both ends of the stator core 30 are locked via the connecting means 360, so that the stator core 30 is formed in an annular shape.

  Note that the stator core bending step does not have to have the engaging recess of the washer 100 described above. Further, if the degree of the perfect circle can be increased to a specified value or more in an insert molding process to be described later, it is not necessary to perform accuracy using the washer 100 in the stator core bending process.

  Next, the insulator 33 is integrally formed on the outer periphery of each of the teeth 32a to 32l of the stator core 30 by insert molding (insulator mounting step). As shown in FIG. 7, in the insulator mounting step, the stator core 30 is inserted along a cylindrical cored bar 200 provided in a mold (both not shown) provided in the insert molding device, and each of the teeth 32 a to 32- The outer peripheral surface of 32 l is integrally covered with an insulator 33. At this time, the stator core 30 is held in a state where the tooth surface 231 and the outer periphery of the back yoke 31 are supported in the mold.

  The cored bar 200 has a cylindrical shape protruding in a mold (not shown), and the surface thereof matches the teeth surfaces 321 of the stator core 30 as guide surfaces. That is, after the annular stator core 30 is inserted into the mold along the core metal 200, resin is poured into the mold and insert molding is performed, so that each of the teeth 32a to 32l has an outer periphery of the tooth surface 321 and the back yoke 31. Insulator 33 is mounted.

  This insulator attaching step also serves as a second centering step that further increases the dimensional accuracy of the stator core 30 by fitting the teeth surface 321 of the stator core 30 to the outer peripheral surface of the cored bar 200.

  That is, by increasing the roundness of the outer peripheral surface of the cored bar 200, the roundness with respect to the teeth surface 321 increases, so that the dimensional accuracy of the stator core 30 itself can be further improved simultaneously with the installation of the insulator.

  After the insulator 33 is incorporated in the stator core 30, the coils 32 a to 32 l are connected with a winding by a coil winding device (not shown) and then connected in a predetermined connection pattern. Thereafter, the stator 3 is integrated with the synthetic resin by insert molding (insert molding step).

  As shown in FIG. 8, in the insert molding step, the stator 3 to which the insulator 33 and the winding 4 are attached is inserted along a cored bar 300 in a mold (both not shown) provided in the insert molding apparatus, This is a step of covering the entire stator 3 with resin.

  The cored bar 300 has a columnar shape protruding in a mold (not shown), and the surface thereof matches the teeth surfaces 321 of the stator 3 as a guide surface. The cored bar 300 has substantially the same configuration as the above-described cored bar 200 in the insulator mounting step.

  That is, after the stator 3 is inserted into the mold along the core 300, the resin is poured into the mold and subjected to insert molding, so that the resin 5 is integrated with the entire stator 3 while leaving the teeth surface 321. Molded.

  At this time, the outer periphery of the stator core 30 is pushed to the inner diameter side by the sealing pressure of the resin poured into the mold. By this pressing force, the teeth surface 321 is pressed against the outer peripheral surface of the cored bar 300, and the roundness of the stator teeth surface is further increased. That is, the insert molding process also serves as a final process for increasing the dimensional accuracy of the stator 3 (the roundness of the stator teeth surface).

  In the present embodiment, the stator 3 is completed through the above-described steps. However, the present invention is applied to a case where an insulator is formed integrally or separately on a stator core 30 in a straight state, and the winding is wound and then bent into an annular shape. May be. In this case, the line area ratio of the winding can be further improved.

  In this embodiment, teeth 32a to 32l are provided in each segment of the stator core 30, but the present invention may be applied to a type of stator core in which teeth are not provided in some segments. .

  As described above, according to the present invention, by increasing the opening angle θ, the straight core can be easily circularized even if the bending fulcrum varies, and a small gap is formed in each notch 35 of the stator 3. Since the stator core 30 is easily deformed and the tooth surface 321 can be easily pressed against the metal core, high dimensional accuracy of the stator 3 can be easily obtained.

1 Electric motor
2 Rotor 3 Stator 30 Stator Core 31 Yoke 32a to 32l Teeth 321 Teeth Surface 33 Insulator 34 Half-Drilled Hole 35 Notch 351, 352 Side Wall Surface 353 Notch 36 Connecting Means 361 Locking Convex 362

Claims (2)

A rotor having a rotary output shaft; and a stator coaxially disposed on the outer periphery of the rotor, wherein the stator has a plurality of teeth protruding from the inner peripheral surface of the annularly formed yoke toward the rotor. The stator core is formed of a plurality of segments including the teeth in a straight line.
A notch is provided between the segments of the stator core to prevent the adjacent segments from interfering with each other when the stator core is bent in an annular shape, and the notch has a notch width. The stator core is formed in a substantially V shape that gradually expands from the outer diameter side to the inner diameter side, and is designed so that the sum of the opening angles θ of the notches is larger than 360 °. In the manufacturing method of the motor formed by connecting each other,
A first step of bending the teeth surfaces of the segments connected in a straight line of the stator core into an annular shape while pressing the teeth surfaces against a cylindrical washer;
A second step of locking both ends of the stator core;
The stator core that has been annularized through the first step and the second step is inserted along a cylindrical first core bar provided in an insulator molding die, and an insulator is placed on each of the teeth. A third step of integrally forming;
A fourth step of applying a winding to each tooth on which the insulator is formed;
Fifth step of inserting the stator core provided with the winding along the second core metal having a cylindrical shape provided in the insert molding die, and covering the entire stator core excluding the tooth surface with resin. When,
A method for manufacturing an electric motor, comprising: At both ends of the stator core, there is provided a connecting means including a concave and convex fitting including a convex portion and a concave portion locked to the convex portion by caulking. In the second step, both ends of the stator core are connected to the connecting portion. The method of manufacturing an electric motor according to claim 1, wherein the motor is locked by means of concave-convex fitting of the means.

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